Archive for June, 2013

Assamo, the Egyptian vulture we fitted with a satellite transmitter in March, continues to provide information. During the past two weeks he has spent his time in southern Djibouti. Over the course of the tracking Assamo’s behavior has been variable, highlighting the importance of flexibility for a scavenging bird, particularly in a desert environment. So, we have seen how Assamo apparently makes use of ephemeral settlements, moving from one to the next. We have seen him commute to what seems to be a reliable food source at the town of ‘Ali Sabieh. We have also seen him move over relatively large distances between north and south Djibouti.

During the first half of June 2013 Assamo has spent a lot of his time perched on electricity pylons. Have a look at the two images below and you can see the pylons on which Assamo roosted (Hint: If you click on the image, it will open up larger in a new window). This highlights a problem that vultures and other birds face: Electrocution. Electrocution can be a significant cause of mortality, especially for large soaring birds. Some pylons designs are more dangerous than others and most of the ones we saw in Djibouti seem to be relatively benign. Indeed, the pylons in these images appear to be large enough so that electrocution is unlikely.

Here is a link to a report from Bulgaria about an Egyptian vulture electrocuted there, and here is one thing the Bulgarian Society for Protection of Birds is doing about it. Still, if you want to read more about this problem, try to dig out this reference:

Thursday, May 24, turns out to be a special day. We catch two adult black vultures simultaneously (yellow wing-tag numbers 18 and 20) at 9:40, but more importantly, we catch and satellite tag three adult turkey vultures, which we name “Desert Rat” after Doug, “Jennie” after Jennie Duberstein, and “T. K. Red River,” after one the three dairy farms that have been providing bait. The three turkey vultures, which are all adults, bring our total of satellite tagged individuals to four. With four days of trapping left we are two-thirds of the way to our goal.

Friday, 25 May, turns out to be far less special. We have birds on the ground at 5:10, and high numbers throughout the day, but no one feeds and at 11 AM we pull the traps with no birds on the ground or in the air. Reality sets in. We have three more trapping days and two more turkey vultures to trap.

Saturday, 26 May, proves to be much more fruitful. At 5:30 AM two turkey vultures fly over, but do not land. Our donor arrives from Tucson for her third visit at 7:30. She has yet to see us trap a turkey vulture, and today, she promises, will be her last visit. The pressure is on.

Linda joins me in the blind at 7:30, and I tell her once again how difficult it can be to trap turkey vultures. At 8, two turkeys arrive at the site, land, and, almost immediately, begin feeding on one of our snared carcasses. Five minutes later the first of two trapped vultures for the day is caught. I run to the carcass as our donor snaps a series of photos. My ancient body speeding across the desert makes for quite a scene. “Linda,” named after our donor, is released 40 minutes later, but not before we catch our second vulture of the day.

“Edward Abbey,” so named for the western conservation writer, is caught at 8:05. Abbey quipped in his masterpiece Desert Solitaire that he wanted his remains placed in the desert so that turkey vultures could feed on it. Whether or not that happened after he died, his namesake now soars above the lands he so wanted to protect for all of us, and our trapping crew…Linda, Julie, Doug, Jennie, Jean Francois, Marc and I, are happy.

After releasing “Edward” we clean up our mess, offer our farewells to our hosts Doug and Julie, and head back to Tucson. We celebrate our victory at an Italian restaurant that evening and plan our routes for a 200-mile road-side count of vultures across the backlands of southeastern Arizona and eastern-most New Mexico that we plan to conduct the next day. The road survey takes us past numerous historic sites, including the place where Geronimo finally surrendered to the U.S. Calvary in the Skeleton Valley near the border with New Mexico in 1886. We also see 24 turkey vultures and return to Tucson that night for a second celebratory dinner. Jean Francois and I return to Hawk Mountain the following day.

Maps of the whereabouts of our tagged birds should appear on Hawk Mountain’s website next week. I have already started planning a trip to the southern cone of South America to capture and tag representatives of the one remaining race of turkey vultures that we have yet to study. Finding the right colleagues to work with will be key to our success in South America, but I am now more convinced than ever that I will find them, and that Cathartes aura jota too will join the other 5 subspecies in our grand studies of turkey vulture migration.

Monday, 20 May, starts off with breakfast at the Holiday Inn Express in Tucson at 5:30 AM, and a final check of our equipment. Doug lives west of Casa Grande in Pinal County, about an hour and a half northwest of Tucson. We arrive at his house just after 9 AM. Loney is extremely animated, and rightfully so. More than 40 turkey and black vultures are feasting on three still-born calves he has set out in the predawn hours, and everything looks just about perfect.

Doug, also known as the “Desert Rat,” tells us that setting out traps straight-off most likely will spook the birds for the day, and we decide to wait until the predawn hours of tomorrow to do so. After discussing how best to set out our traps, Doug and I make the rounds and pick up four still-born calves at three local dairy farms (which, in actuality, are huge, industrial-style operations with tens of thousands of cows) that will serve as tomorrow’s bait. We then spend the afternoon looking at the vultures feeding at the site before heading back to Casa Grande to check into yet another Holiday Inn Express that will serve as our home-away-from-home for the next week. Dinner is early and we are in bed at 9 PM anticipating a predawn trip back to the trap site.

Although we have decided to focus on trapping turkey vultures, we also have managed to get permission from both the Game and Fish Department of the State of Arizona and the Federal Government’s Bird Banding Lab to wing-tag any black vultures we catch at the site. Black vultures tend to dominate turkey vultures as feeding sites and the idea behind adding them to our permits was to not miss the opportunity of collecting data on the movements of this species should we catch them.

We arrive at Doug’s shortly before 5 AM and set out the carcasses and traps. We then retreat to a blind that Doug has set up and wait for the birds. The first turkey vulture arrives before 7 AM and the first black vulture arrives shortly after 8. A reporter and photographer from the Arizona Republic newspaper arrives at 7:30 and just before 8:30 one of the several dozen 80-lb test monofilament nooses festooning the three carcasses snares a second-year black vulture.

Jean-Francois and I race from the blind to secure it. In less than half an hour we release the bird with a bright yellow wing tag numbered 269 on its right wing. We also take a small sample of blood to determine the sex of the bird and to learn whether or not it is contaminated with lead, the toxic heavy metal that is currently compromising efforts to reintroduce California condors in the American South West. The reporter and photographer are happy, as are we … at least initially.

Keith “preparing” a still-born calf for use in the trapping.

Unfortunately, the capture spooked the remaining vultures from the site and none return to continue feeding. We again make the rounds to pick up bait for the next day and leave for the hotel in mid-afternoon with no birds in sight. The plan is to get to the site earlier the next day and trap more birds.

Wednesday 22 May has us in the blind and waiting for birds at 5 am. The first turkey vulture arrives at 5:55, and there are seven at the site by 6:05. Wednesday is garbage day at Doug’s, and his wife Julie has been sent half a mile down the road with the trash can to intercept and divert the garbage truck so that it doesn’t flush the birds when it collects the trash in front of Doug’s house.

We catch our first turkey vulture, which we name “Julie” in honor of Doug’s wife, at 7:20. Several vultures return to the site less than 15 minutes later. Marc, Jean-Francois, and Jennie work together to harness the bird, and it is in the air and flying normally by at 8:35. Unfortunately we again fail to catch a second vulture that day.

After wringing our hands for most of the afternoon, we devise Plan B. First we bury all of the carcasses that have been accumulating at the trap site. As you can well imagine, the carcasses decompose quickly in the hot desert and both the stench that accompanies them and the flies they attract become more than a minor nuisance. It’s hard work, but the silty and rockless soil is relatively easy to dig, and by the time we leave the site in late afternoon, it is much cleaner than before. The two new carcasses that we place out quickly attract several dozens of birds and Doug reports to us that by dusk most of the new food has been consumed. Our plan for tomorrow–as recommended by Doug–is to have “Boots on the ground at 4:15” and two (not three or four) new carcasses with snares in place by 4:45. By the time we return to our hotel we are upbeat, but still a bit nervous, as we are well behind schedule.

Over the course of the last decade my colleagues and I have attached satellite-tracking devices on more than 30 turkey vultures and then followed their movements across North, Central, and South America. Included in the mix have been individuals representing three of the six recognized subspecies: the Cathartesauraseptentrionalis race that breeds in Pennsylvania, the C. a.meridionalis race that breeds in the Pacific Northwest and central Saskatchewan, and the C. a.ruficollis race that breeds in central Argentina.

We also have wing-tagged more than 500 individuals in these areas, as well as in Venezuela and the Falkland Islands where a fourth race, C. a.falklandica, breeds. That said we have yet to study movements of the two remaining subspecies of turkey vultures, C. a. jota and C. a. aura.Jota occur in South America’s “southern cone,” and aura ranges from the southeastern-most corner of the United States through Mexico and Central America.

The movement data that we have collected so far indicate that the four races we have studied exhibit distinctively different migration geographies, which we are currently analyzing in detail. Our long-term goal, however, is to place tracking devices on individuals of all six races so that we can better understand variation and flexibility throughout the movement ecology of this, the world’s most successful, scavenging bird of prey.

Late last year we received funding to tag six individuals of the Cathartes aura aura subspecies. If all goes according to plan, we will do so this week. As I draft this entry, Hawk Mountain’s Senior Research Biologist, Dr. Jean-Francois Therrien, and I are on our way to Tucson, Arizona where we will meet up with Dr. Marc Bechard, Distinguished Professor of Biology at Boise State University, and Dr. Jennie Duberstein, Education and Outreach Coordinator with the USF&WS Sonoran Joint Venture Project, to plan the details of our trapping effort. Simply put we need to catch and tag six birds in eight days. Although it sounds simple enough, none of us has ever worked with vultures in the American Southwest and I, for one, am a bit apprehensive.

Jennie has laid the ground work for a successful effort by locating and convincing a local land owner to serve as our on-site logistical coordinator. Although I have yet to meet Doug Loney, Jennie assures me that he has been pre-baiting a site in front of his home in the Sonoran Desert for more than a month, and that upwards of 80 turkey and black vultures have been visiting it regularly. The forecast for the coming week calls for sunny and hot weather, and our team is “pumped” up and ready to go. Tomorrow we will visit the site.